The present invention relates generally to scroll-type machines. More particularly, the present invention relates to hermetic scroll compressors incorporating a fluid injection system where the fluid injection system utilizes a fluid passage extending through the end plate of the orbiting scroll member.
Refrigeration and air conditioning systems generally include a compressor, a condenser, an expansion valve or an equivalent, and an evaporator. These components are coupled in sequence in a continuous flow path. A working fluid flows through the system and alternates between a liquid phase and a vapor or gaseous phase.
A variety of compressor types have been used in refrigeration systems, including but not limited to reciprocating compressors, screw compressors and rotary compressors. Rotary type compressors can include the various vane type compressors as scroll machines. Scroll compressors are constructed using two scroll members with each scroll member having an end plate and a spiral wrap. The scroll members are mounted so that they may engage in relative orbiting motion with respect to each other. During this orbiting movement, the spiral wraps define a successive series of enclosed spaces or pockets, each of which progressively decrease in size as it moves inwardly from a radial outer position at a relatively low suction pressure to a central position at a relatively high pressure. The compressed gas exits from the enclosed space at the central position through a discharge passage formed through the end plate of one of the scroll members.
The designers for these scroll-type machines need to have access to these enclosed spaces or pockets as they move between suction and discharge for various reasons. One reason for accessing these moving pockets is to inject oil into the pockets in order to lubricate and cool the scroll members as they compress the fluid. Another reason for accessing these moving pockets, for a refrigerant compressor, is to inject liquid refrigerant to provide cooling for the scroll members. Another reason for accessing these moving pockets is to connect these intermediate pockets to the suction zone of the compressor in order to reduce the capacity of the compressor in a capacity modulation system. Still another reason for accessing these moving pockets is to inject an additional quantity of the fluid being compressed in vapor form in order to increase the compression ratio or capacity of the scroll machine.
Various prior art methods have been utilized to gain access to these moving pockets. When the access to these moving pockets does not require access from outside the hermetic shell of the compressor, such as oil injection and/or capacity modulation, the access can be achieved through either the orbiting scroll or the non-orbiting scroll, depending on the design intent for the injection system. When the access to these moving pockets does require access from outside the hermetic shell, such as liquid injection and vapor injection systems, the access is provided through the stationary or non-orbiting scroll due to the ease of communicating with a stationary scroll member rather than the moving orbiting scroll member.
The continued development for fluid injection systems include the optimizing of the designs for gaining access to the moving pockets of compressed fluid. The present invention provides the art with a method of accessing the moving fluid pockets from outside the hermetic shell of the compressor through a passage extending through the end plate of the orbiting scroll member. Accessing the moving pockets from outside the hermetic shell through the orbiting scroll provides for less expensive and simpler assembly of the scroll machine as well as less expensive machining requirements for the scroll members.
Other advantages and objects of the present invention will become apparent to those skilled in the art from the subsequent detailed description, appended claims and drawings.